There often occurs a need to create or re-create a schematic diagram of a circuit already realized in printed-circuit form. Such a need may occur because the original schematic has been lost or damaged, or, perhaps more commonly, because modifications and revisions to the circuit have been made over time but not reflected in the original schematic.
Regardless of the reason for the need, current practice requires that a schematic be created manually by correlating all parts and connections on the printed circuit board. This process is time-intensive, tedious, and prone to error.
A marked disadvantage of creating schematics manually is the inherent inflexibility in this process. Once created, such a mechanical schematic does not lend itself readily to modification nor to reorganization.